The GaSb(001) surface prepared by ion bombardment and annealing is investigated by angle-resolved photoemission spectroscopy using He i and synchrotron radiation with photon energies between 9 and 34 eV. The band structure is traced along the Γ-Δ-X line normal to the surface and along lines of high symmetry of the surface Brillouin zone by measuring the energy-distribution curves and constant-initial-state and constant-final-state spectra. The results are compared with theoretical bulk band structures; in particular, the normal-emission data were analyzed by using structure plots, and in this way the most dispersing features in normal emission could be explained. Furthermore, several surface states or resonances are found showing the dispersion of a reconstructed surface. The spectral features of constant-initial-state spectra reflect mainly the band edges of the unoccupied bulk band structure and are probably associated with emissions from a surface state or backfolded bulk bands close to the ${\mathit{X}}_3$ critical-point energy. The decay of the Ga 3d core exciton is observed in constant-final-state spectra, indicating the existence of an unoccupied surface state at the Ga-rich surface.

• Received 6 February 1991

DOI:https://doi.org/10.1103/PhysRevB.44.6312